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ISO 14704:2016 pdf free

ISO 14704:2016 pdf free.Fine ceramics (advanced ceramics, advanced technical ceramics)一Test method for flexural strength of
monolithic ceramics at room temperature
Three-or four-point flexure configurations shall be used, as illustrated in Figure 1. The four-point-1/4 point configuration is recommended. The fixture shall have bearings that are free to roll, as described in 5.2.2, in order to eliminate frictional constraints when the test piece surfaces expand or contract during loading. In addition, the fixture shall be designed so that parts “articulate” or tilt to ensure uniform loading to the test piece. The articulation is designed so that parts of the fixture can rotate, as shown in Figure B.1, to ensure even loading on the left and right bearings. An articulation is also needed to ensure that all the bearings evenly contact the test piece surfaces and apply uniform load. Semi-articulated fixtures have some articulating or tilting capabilities and may be used with test pieces that have flat and parallel surfaces, such as on as-machined test pieces. A semi-articulating fixture has pairs of upper and lower bearings that articulate to match the test piece surfaces, as shown in Figures B.2 and B.3. Fully articulated fixtures have more moving parts and are necessary for test pieces that do not have flat and parallel surfaces. They allow independent articulation of the bearings. Fully articulated fixtures often are necessary for as-fired, heat-treated or oxidized test pieces, since uneven loading can cause twisting and severe errors. A fully articulating fixture may also be used with machined test pieces.
NOTE 1 Friction can cause errors in the stress calculations. The rolling can be accomplished by several designs. The bearing can be mounted in roller bearing or cylindrical bearing assemblies. It is also acceptable, and simpler, for the bearings to be free to roll on the fixture surface, as shown in Eigure 2. The bearing diameter is specified on the basis of competing requirements. The bearings should not be so large as to cause excessive change in the moment arm as a test piece deflects, as this can create errors from contact-point tangency shift. On the other hand, the bearings should not be so small as to create excessive wedging stresses in the test piece or create contact stresses that damage the fixture.ISO 14704 pdf free download.

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